BOSTON — THE voice at the other end of the telephone is jubilant. Giggles break out in mid-sentence. Agraspina Manso Gueverra, a Cuban refugee, savors her two-week-old freedom after 11 years in prison.Ms. Manso was one of the original 125,000 Mariel boatlift people who arrived in Florida between April and October 1980. She fled Cuba only to land in a refugee camp, then was bounced from prison to prison after an unsuccessful attempt by US Immigration and Naturalization Service (INS) officials to place her with a family. She was then 20 years old. Manso's plight highlights the most troubling aftereffects of US immigration policy throughout the Mariel boatlift saga. Detainees are being held in prison with no fixed sentence, even without criminal conviction or other evidence suggesting they would endanger American citizens. She fell through every conceivable crack in our criminal justice system, says Gary LeShaw, a legal-aid attorney for the Atlanta- based Coalition to Support Cuban Detainees. At the very least, her case is extreme, say both INS officials and representatives from the United Methodist Committee on Relief in New York City, who sponsored her release from the federal penitentiary in Lexington, Ky., after discovering her there six months ago. Her release comes at an opportune time, says Mr. LeShaw. Congress begins hearings Oct. 10 to determine some of the causes for the recent prison riots at the Talledega Federal Correctional Institution, in Talledega, Ala. Her story might possibly spur change in the policies that led to her incarceration for so long, say her sponsors. The courts have held that the Marielitos have no legal status. "They are excludable aliens," says LeShaw. "Legally, they're not here and they're not entitled to due process. This is ridiculous." Manso sat in prison for years, but unlike her male counterparts in other federal prisons, she did not riot, he says. The hearings will seek to establish if the detainees "have been accorded basic human rights," says Rep. William Hughes (D) of New Jersey, the new chairman of the subcommittee on Intellectual Property and Judicial Administration. The committee has jurisdiction over Cuban detainees. It is important that Congress understand what the INS processes are "when they determine to carry a case forward year after year," for whatever reason, he says. "What you have are stateless people like Manso," says Sally Sandidge, a paralegal with Atlanta Legal Aid. "What do you do with stateless people when neither country wants them and they are not capable of functioning well on their own?" she asks. Cuban-Americans don't identify with these people any more than most Americans identify with anyone else in prison, she says. Most of the arrivals from Mariel easily merged into American society as millions of immigrants previously did, says Duke Austin, spokesman for the INS in Washington. Others, who were mental patients or who were emptied from Castro's jails, were screened by INS officials to be repatriated. Those who committed crimes after arriving here were also held for possible deportation. The INS wanted to deport 2,746 of these detainees. Fewer than 15 of the original 125,000 Marielitos "have never had a chance to walk free," says Mr. Austin. "What do you do when aliens cannot make the adjustment," to life in US society he asks, adding that Manso is "a tough case," on which to judge INS procedures. Disputes with Castro over official US establishment of Radio Marti in 1984, (a station broadcasting from Florida with the intent of undermining Castro) ended Cuban acceptance of the detainees' return. In 1987 diplomatic breakthroughs resulted in a resumption of deportations. When prisoners rioted at the federal penitentiary in Atlanta and in Oakdale, La., in 1987, one of the agreements that ended the riots was a reform of the process for reviewing the status of the Mariel Cubans who ran into trouble with the law. In addition to INS standard hearing procedures on whether jailed and detained Mariel Cubans should be paroled into US society, there was a second-tier review ordered by then-Attorney General Edwin Meese to allow for appealing adverse INS decisions to a panel of Just ice Department officials. Since 1987, under the amended process, more than 1,800 of the Cuban detainees originally on the list of those to be deported have been paroled. Since then 270 have run afoul of the law and been returned to prison. Another 457 have been deported to Cuba. But there is still no due process, says LeShaw. What causes despair on the part of detainees is that an INS hearing simply reaffirms their powerlessness, he says. They have no lawyer present with them to argue their cases and the decision is made by an anonymous panel back in Washington. If this policy is continued, LeShaw warns, it will lead to further prison riots.